Optical imaging of metallic and semiconductor nanostructures at sub–wavelength regime

A. K. Sivadasan, Kishore K. Madapu and Prajit Dhara

Nanomaterials Characterization and Sensors Section, Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam-603102, India

The near-field scanning optical microscopy (NSOM) is not only a tool for imaging of objects in the sub-wavelength limit but also a prominent characteristic tool for understanding the intrinsic properties of the nanostructures. The effect of strong localized surface plasmon resonance absorption of excitation laser in the NSOM images for Au nanoparticles is observed. The role of electronic transitions from different native defect related energy states of AlGaN are also discussed in understanding the NSOM images for the semiconductor nanowire.